Combined shield and illuminating means for grinding wheels



Dec. 23, 1941. s. A. BROWN COMBINED SHIELD AND ILLUMINATING MEANS FOR GRINDING WHEELS Filed Jan. 11, 1940 2 Sheets-Sheet l Dec. 23, 1941. s. A. BROWN 2,267,189

COMBINED SHIELD AND ILLUMINATING MEANS FOR GRINDING WHEELS Filed Jan. 11, 1940 2 Sheets-Sheet 2 FIB. .Z 3 FIE-r. 5

I I l I Patented Dec. 23, 1941 COMBINED SHIEIJ) AND ILLUMINATING MEANS FOR GRINDING WHEELS Steflen Brown, Dayton, Ohio, assignor to The Brown-Brockmeyer 00., Inc., Dayton, Ohio, a

corporation of Ohio Application January 11, 1940, Serial No. 313,310

7 Claims.

This invention relates to a grinder and more particularly to means associated with the grinder for lighting the wheel and the work and means associated therewith for shielding and arresting sparks thrown off by the grinding wheel.

The principal object of the present invention is to provide a combination spark shield and lamp for illuminating the wheel and the work; by combining the spark arrester with the lamp housing, the most convenient and efiective way of illuminating the work and arresting sparks is brought about.

Another object is to so construct and arrange the light and'the light housing that a maximum illumination of the wheel in the area of grinding is attained and at the same time the passage of light from the lamp directly to the eyes of the operator is prevented, thus eliminating glare; it is preferred to project the light from the lamp directly onto the work area and to reflect it therefrom to the operator's eyes, thus insuring maximum illumination and minimum glare, the front of the lamp housing being so disposed that no light can pass directly from the light bulb to the operator's eyes.

Another object is to provide a lamp for illuminating the wheel and the work which is integral with the grinder.

Still another object is to employ in the combination described above a bayonet type of lamp and lamp socket which prevents the lamp from working loose from vibration.-

Another object is to provide a resilient mounting for the lamp whereby long life of the lamp is insured by protecting the lamp filament from vibration; at the same time, the lamp is so disposed within the housing therefor that it is protected from injury and is not likely to be broken by accident while the bulb is easily renewed.

Another object is to provide a low voltage lamp which is energized from the main power line which supplies the electric motor rotating the grinding wheel; since the motor is operated at relatively high voltage, say 110 or 220 volts, while the lamp voltage is from 6 to 8 volts, means is-provided requiring no separate external connection for taking off electrical energy at the desired low voltage from the main power line within the grinder and for supplying the low voltage power thus taken 01f to the lamp; this result may be accomplished in several ways, some of which will be more fully described below.

Still another object is to provide for adjustment in a single operation of the spark shield and thereby the lamp carried integrally therewith to wards the grinding wheel whereby to compensate for "wear of the grinding wheel or for the substitution of diiierent sized wheels; thus it is insured that the spark shield and the lamp are moved together in a single adjusting operation and that the shield and. lamp are maintained at the same distance apart from one another and are by a simple and convenient adjusting operation maintained at the same distance from the wheel; thus it is insured that a constant sparkshielding effect is maintained and a constant illumination of the wheel and the work is effected, while the illumination is kept in the proper place on the working area.

Other objects of the present invention will hereinafter appear.

In the accompanying drawings,

' Fig. 1 is a perspective of a grinder having two grinding wheels, each of which is equipped with apparatus embodying the principles of the present invention.

Fig. 2 is a fragmentary sectional view of the wheel, the wheel housing and the combined spark shield and lamp housing; this view shows how the lamp projects its light onto the working area without causing glare in the eyes of the operator.

Fig. 3 is a view taken on the line 33 of Fig. 2 looking in the direction of the arrows.

Fig. 4 is a detailed sectional view showing the resilient mounting of the lamp bulb and is taken on the line 44 of Fig. 2, looking in the direction of the arrows.

Fig. 5 is a detailed sectional view taken on the line 5-5 of Fig. 2 looking in the direction of the arrows.

Figs. 6 to 8 are diagrammatic views showing various electrical hook-ups for taking of! the low voltage for operating the lamp bulbs. from the high voltage supplied to the electric motor of the grinder, Fig. 6 showing the utilization of a winding of the motor as the primary of a transformer, a secondary of which is employed to light the lamp bulbs, the motor winding additionally performing its function in causing rotation of the motor. Fig. '7 shows a-built-in step-down transformer operated across two of the three-phase power lines. Fig. 8 shows a three-phase motor wherein the low voltage is tapped ofi of one of the motor windings between the neutral point and the tapping point.

Referring to the accompanying drawings in detail, I designates the base of the grinder upon which is mounted the motor 2 which has fixedly carried upon its-shaft in any suitable manner and at the opposite ends thereof, the two grind-.

ing wheels I. The grinding wheels 2 are rotatably driven by the motor 2 in the usual manner. Surrounding each of the grinding wheels is a partially encircling wheel housing 4 which is secured in any desired. manner on its inward faceto the housing of motor 2. The housing 4 has formed integrally therewith the hollow discharge caslng I which is of the usual type. Ad- Justably positioned adlacent the periphery of the wheel 3 is the steady rest I which may be adlustably mounted in any desired manner upon the wheel housing 4.

Coming now to the description or the spark shield and lighting means, I designates the spark shield or arrester which is mounted radially ofthe wheel 2 and which is adiustably secured to the housing 4 by means of the cap screws I which pass through outwardly extending parallel slots 9 in the spark shield 1 into threaded reception within bosses III integrally formed with the wheel housing 4. The spark shield I is mounted so as to be supported along the upper face ll of the wheel housing 4 within the opening formed therein for access to the grinding wheel. Normally the shield 'I isadiusted so that its radially inward race I2 is closely adjacent the periphery of the wheel 2 so that the passage of sparks along around the wheel into the working area is substantially prevented.

The shield I has integrally formed thereon a lamp housing. The shield 1 acts as the rear wall of this housing and cooperates with the top it, front I4 and sides I! to form a lamp housing which is adapted to project light onto" the upper exposed portion of the grinding wheel whereby to illuminate this portion of the wheel and the workpiece held thereagainst. In order to support the lamp socket and the lamp bulb within this housing at the proper positlorninwardly extending bosses i6 (Fig. 2) are provided integrally with the front face i4 of the lamp housing. Across these bosses It, a strip ll of resilient material such as rubber is mounted by means of the screws l8 which are accessible from the front of the lamp housing, projecting through the front wall i4 thereof. Rubber strip i1 is of semisoft rubber, and has suillcient hardness to receive the threads of screws it, but is sufficiently resilient to prevent the transmission of vibration or shock to the bulb. Rubber strip I! may or may not be corded. This strip also performs an elec-- trical insulating function by insulating the base and socket of the bulb from the metal lamp housing and thereby from the machine. Mounted intermediate of this rubber strip i'l by means of ..the bolt [9 is a spring clip 20 which is adapted to detachably surround the lamp socket 2| and hold it securely in place. The lamp socket 2| is of the bayonet type and is adapted to receive the conventional low voltage lamp 22 which has the usual bayonet type base 22. The base 22 is of the usual metal construction and is connected as .usual to one side of the lamp filament. In order-toestablish electrical connection to this base'without-connecting the lamp housing to the electrical source, the lug 24 is mounted between the clip 20 and the rubber strip l'l around the bolt l8 and an insulated wire 25 connects to this clip 24 and leads rearwardly through an insulating bushing 28 mounted in an aperture in the upper portion of the spark shield I.

Electrical contact is made to the other side of the bulb 22 by means of the centrally located contact member 21 which is mounted in the in-. sulating washer and sleeve 28 slidably mounted adjacentthebottomofthesocketll. 'Ihismem ber 2l-isnormallyurgeddownwardlyhythe silient spring 22. The contact 21 is connected to an insulated wire 8| which leads rearwardly through the insulating llintheshieldl.

From the foregoing, it will be.' seen that lamp and the spark shield are adjustable wardly or outwardly as a unit so as to of wearof thegrindingwheelandsoas for substitution-of grinding wheels of diilerent diameter. It will further be seen that advantageous because it is desirable to have the grinder. It is impossible for any of the light go from bulb 22 to reach the operator's eyes except by reflection from the grinding surface or the workpiece. This results in very high illumination of the working area without glare. nae dotted lines in Fig. 2 indicate that the lisht from bulb 22 is proiected onto the working area and is then reflected outwardly towards the operator. Thus, the zone of maximum lighting is right in the area of grinding.

It is preferred that bulbs 22 be of the low voltage type since such bulbs are commercially available with the bayonet type base which insures against their coming loose due to vibration. Furthermore. the space available in the lamp housing is so small that it would be impracticable to use a large high voltage bulb therein. Accordingly, means is provided which is integral with the grinder itself and which requires no separate electrical connection to the power lines for supplying low' voltage electricity 0 to the bulbs. Thus, by a single operation ofplugging in a single cord, nergization of the electric motor 2 and of the bulbs 22 is assured. In Figs. 6 to 8, there are portrayed several ways in which low voltage current may be derived without requiring a separate attachment to the power mains.

In Fig. 6, the electric motor has the winding 3| which is adapted to be connected across the power lines 32 by means of the switch 21 and which is adapted to cause the motor to rotate. The winding 2| may be either a rotor or a, stator windinga Provision is made for causing this winding 2| to additionally function as the-primary of a step-down transformer, the secondary 24 of which is placed closely adjacent the winding II. If winding 3! is a rotor winding, slip rings must be provided for taking 01! the current induced in secondary 24. The current induced in secondary 24 is connected by .the wires 2' and 30 to the bulbs 22. Since the bulbs 22 are normally of low wattage rating, the disposition of the secondary winding 34 adjacent the high voltage motor winding 3! will not interfere appreciably with the operation of the motor. It will be understood that the motor is a singlephase motor of any suitable time. the showing in the drawings being merely diagrammatic.

In Fig. 7, the three-phase lines II are adapted to be connected by the switch 21 to the threephase motor having the Y-connected windings it. On the motor side of the switch 31, a stepdown transformer 12 is disposed, its primary being connected across two of the leads to the windings 3t and its secondary being connected to the wires 25 and," which lead to the lamps :2; ,Thus, the lamps. and the motor ar controlled by a single'switchjfl and' thenecessity for any external connection" other'than' that which would normally be mad to the grinding motor is eliminated,

In Fig. 8, the incoming power lines 35 are connected' by the switch 31 to thewindings 36 of the motor which are connected in Y as before. In order to provide the necessary low voltage for thelamps 22, the line 30-is connected to the neutral point 39 while theline 25 is connected to a point 40 on one of the windings 36. By

thus tapping one of the motor windings, the re- '2 where the connections of Figs. 6 and 8 are employed. Where the connection of Fig. 7 is employed, the step-down transformer 38 is desirably located in the base I of the grinder, proper connections being made thereto. The switch for the control of the grinder is designated as 31 in Fig. 1 and is of the start-stop type.

From the foregoing, it will be seen that the present invention provides a highly useful and convenient method for shielding against sparks and for illuminating the work-ing area of the grinding wheel and that the objects set forth above are effectively attained by the application of the principles of the present invention. It is to be understood, however, that the invention is not limited to the specific form illustrated in the drawings, but that modifications may be made therein to adapt it to varying, conditions and uses without departing from the inventive thought which is to be limited only as set forth in the appended claims.

Having thus fully described my invention, what I claim as new-and desire to secure by Letters Patent is:

1. A grinder comprising a grinding wheel, a housing therefor, a cut-out portion on said housing whereby a portion of said grinding wheel is exposed to the work to be ground, a combined spark arresting shield and lamp housing therefor, having rear wall means, said rear wall means including an extension, means for mounting said extension on said grinding wheel housing above said grinding wheel and in line with the upper rear face of the cut-out portion thereof, said last named means including adjustable means for adjustably mounting said extension and lamp housing to be adjusted toward and away from said grinding wheel, and means for mounting a lamp in said lamp housing whereby to illuminate the exposed portion of the grinding wheel.

2. A grinder comprising a grinder wheel, a housing therefor, a cut-out portion on said housing whereby a portion of said grinding wheel is exposed to the work to be ground, said cut-out portion having upper and lower faces, a combined spark arresting shield and lamp housing having rear wall means, said rear wall means including an extension, means for adjustably mounting said extension above said grinding wheel and in line with the upper face of said cut-out portion of said grinding wheel housing,

the grinding wheel."

3.A grinder comnrismgt; grinding' whe'el} housing therefor} a cut-but portion onsaid' hous-' ing whereby a' portion 'of"said 'grindirigwheelf is exposed to the work to be groundfaTcomf bined spark arresting shield and *lamp' housing therefor, having rear wall means, said're'ar' wailmeans including an extension, means for mounting said extension on said grinding wheel housing above said grinding wheel and inline with the upper rearface of the cut-out portion thereof, said last named means including adjustable means for adjustably mounting said extension and lamp housing to be adjusted toward and away from said grinding wheel, a resilient lamp support in said housing, means for mounting a lamp in said lamp support whereby said lamp illuminates the exposed portion of the grinding wheel.

'4. A grinder comprising a grinding wheel, a housing therefor, a cut-out portion on said housing whereby a portion of said grinding wheel is exposed to the work to be ground, a combined spark arresting shield and lamp housing therefor, having rear wall means, said rear wall means including an extension, means for mounting said extension on said grinding wheel housing above said grinding wheel and in line with the upper rear face of the cut-out portion thereof, said last named means including adjustable means for adjustably mounting said extension and lamp housing to be adjusted toward and away from said grinding wheel, a resilient lamp support in said housing including a rubber strip, means for securing the ends of said strip to said housing, the middle portion of said strip being free from said supporting means, a lamp socket mounted in the said middle portion ofsaid strip,

a lamp secured in said socket, whereby said lamp illuminates the exposed portion of the grinding wheel.

5. A grinding wheel, a housing therefor, said housing having a cut-out portion whereby a portion of said grinding wheel is exposed to the work to be ground, a combined spark arresting shield and lamp housing having a plurality of walls, the rear wall forming said spark arresting shield, said last named wall having an extension thereon, extending toward said grinding wheel, means for mounting said extension above said grinding wheel and in line with the upper rear face of said cut-out portion of said grinding wheel housing, and means for mounting a lamp in said lamp housing whereby to illuminate the exposed portion of said grinding wheel.

6. A grinding wheel, a housing therefor, said housing having a cut-out portion whereby a portion of said grinding wheel is exposed to the work to be ground, a combined spark arresting shield and lamp housing having a plurality of walls, the rear wall forming said spark arresting shield, said last named wall having an extension thereon, extending toward said grinding wheel, means for mounting said extension above said grinding wheel and in line with the upper rear face of said cut-out portion of said grinding wheel housing, said last named means including adjustable means for adjusting said spark arresting shield and said lamp housing toward and away from said grinding wheel.

w br i'te gil n a i iflamb h fl 1 be adjustedftoward 'an'd awayiffom wheel, and a lamp in said lamp housingwhereby" said lamp illuminates jtheffexposed portion of;

- ing said extension on said grinding wheel housing above saidgrinding wheel and inline with the upper rear face of the cut-out portion thereof, said last named means including adjustable means for adjustably mounting said extension and lamp housing be adjusted toa ward and away from said grinding wheel, and

means for mounting a' lamp lamp housing whereby to illuminate 'the portion of the grinding wheel, a low voltage lamp mounted in said lamp housing. aj shalt, a motor mounted on said shaft said grinding wheel being mounted on said shaft, and an electric circuit connected to said motor and saidlow voltage 10 lamp. 

